package com.weiliai.chapter13;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.socket.DatagramPacket;
import io.netty.handler.codec.MessageToMessageDecoder;
import io.netty.util.CharsetUtil;

import java.nio.charset.StandardCharsets;
import java.util.List;

/**
 * <p>
 * 13.6 LogEventDecoder
 *
 * @author LiWei
 * @since 2022/5/7
 */
public class LogEventDecoder extends MessageToMessageDecoder<DatagramPacket> {

    @Override
    protected void decode(ChannelHandlerContext ctx, DatagramPacket datagramPacket, List<Object> out) throws Exception {
        ByteBuf data = datagramPacket.content();
        int idx = data.indexOf(0, data.readableBytes(), LogEvent.SEPARATOR);

        String filename = data.slice(0, idx)
            .toString(StandardCharsets.UTF_8);
        String logMsg = data.slice(idx + 1, data.readableBytes())
            .toString(CharsetUtil.UTF_8);

        LogEvent event = new LogEvent(datagramPacket.sender(), System.currentTimeMillis(), filename, logMsg);
        out.add(event);
    }
}
